Myst comic: issue zero
The prequel of the Myst comic #1, entitled Passages. It was written by Chris Ulm and drawn by Kirk Van Wormer.
It features Atrus writing a journal, recollecting his memories with his father Gehn during his childhood. He then proceeds to the main story, a legend of D'ni about the story of Varsil, the first D'ni Guildmaster who discovered and perfected the Art, and his apprentice Atak.
The comic is out of production because it was frowned upon by Cyan, owner of the Myst franchise, as well as by Myst fans, as the comic was not faithful or consistent to the Cyan spirit, and known D'ni history. For example no King Clevis ever existed, The Art was known before the D'ni arrived on earth, and Guildmasters existed even before their known history (no 'first' one was ever conceived).
On the other hand, since the story is presented as a 'legend', the reader can still enjoy it as an imaginary tale that was told among D'ni.